Hollywood debut for Aussie wasp likely to be a fizzer

The imminent release of Australian native wasps in California to control defoliating insects destroying California redgums, has small chance of success according to an Australian entomologist.

Dr Grant Farrell, from CSIRO said the release of 100 parasitic female wasps in a North Hollywood park, scheduled for today, is unlikely to control the population of the redgum lerp psyllid, Glycaspis brimblecmobei, also native to Australia, as the life-cycles of the two species are unlikely to remain synchronised within their new environment.

Dr Farrell said this a common problem associated with biological pest control. "The relationship between the target species and the control agent in their natural environments, is dependent upon the synchronisation of their life cycles. When these species are put into a different ecosystem, this synchronisation is often lost".

In Australia the psyllid produces four generations within a 12 month period, with successive generations laying eggs in October, December, February, and April, with six months inactivity over the winter. Dr Farrell said, "What this species is doing in California is anyone's guess".

"In a changed environment species will adapt and it is unlikely they will behave in exactly the same way as they did in their natural environment."

Given that a similar behavioural change can be expected from the the wasp, the chances of the life-cycles remaining synchronised are described by Dr Farrell as "only one chance in four".

However, University of California, Berkeley scientist, Donald Dahlsten, believes the introduction of the wasp will successfully control California's psyllid population.

The two species have been monitored for the past 12 months and it has been seen that the wasps lay their eggs inside the body of the herbivorous insects, which kills them.

Dahlsten believes the chances of success are so high that additional releases beyond today will be unnecessary.